The Australian-born media mogul described it as the "most humble day of my life." But his conclusions during an afternoon of grilling by British lawmakers Tuesday in the shadow of London's Big Ben were anything but.

Summoned to give evidence before Parliament, Murdoch tried to undo some of the damage caused by a newspaper debacle that has spread to politicians and the police, morphing into one of the worst national crises in recent British memory.

At times vague and frail-looking, at others pugnacious and curt, Murdoch denied any knowledge of rampant cellphone hacking by the News of the World. His son James, called to appear with him, did the same in a sometimes-stumbling performance. And even as questioners tried to get him to accept some responsibility for what happened, the 80-year-old billionaire declared he was "the best person" to clean up the mess.

In the end, after three hours of sparring, neither side of the table in the staid committee room seemed to land a knockout punch. The person who came closest was Murdoch's wife, Wendi, who sprang from her chair in back of her husband to smack an activist as he hurled shaving cream onto her husband.

"Mr. Murdoch, your wife has a very good left hook," lawmaker Tom Watson said in a rare moment of levity in the proceedings. (For the record, she swung with her right arm.)

The packed session had been hotly anticipated since Murdoch and his son were summoned Thursday to give evidence before Parliament. Analysts expected it to be the most-watched parliamentary committee hearing in history.

People lined up early for tickets to see the man who trafficked in sensational headlines become one himself. A group of protesters, some wearing Rupert Murdoch masks, thronged the area outside the building. Some waved placards reading, "Smash Murdoch's evil empire!"

For the Murdochs, it was a chance to make a public atonement for the News of the World's accessing of private voicemails of potentially thousands of people, including not just celebrities and political bigwigs but also murder victims and fallen soldiers. In response to a public outcry, Murdoch shut down the tabloid two weeks ago.

For members of Parliament, the committee hearing was their moment to demonstrate that they no longer stood in thrall to a man who has intimidated plenty of British politicians through the power of his newspaper holdings.

In a statement, Murdoch apologized to the hacking victims.

"I want them to know the depth of my regret for the horrible invasions into their lives. I fully understand their ire. And I intend to work tirelessly to merit their forgiveness," he said.

But he had to endure some sharp questions from lawmakers, particularly Watson, who were intent on unveiling whether Murdoch fostered a culture of criminal recklessness at News International, the British subsidiary of News Corp., which also owns the Times of London and the Sun newspapers.

Murdoch said he had zero tolerance for lawbreaking but acknowledged that he might have taken his eye off the tabloid.

"The News of the World is less than 1% of the company," Murdoch said. "I employ 53,000 people around the world … and I'm spread watching and appointing people whom I trust to run those divisions."

He dismissed suggestions that he and his top executives had been "willfully blind" to what went on.

"I've heard the phrase before, and we were not ever guilty of that," Murdoch said. "I feel that people I trusted — I'm not saying who, I don't know what level — have let me down.... And it's for them to pay."

But he and his son both strongly backed two senior News Corp. executives who have stepped down as a result of the scandal: Les Hinton, the chief executive of Dow Jones, and Rebekah Brooks, the head of News International and the editor of the News of the World at the time the tabloid is suspected of intercepting and tampering with voicemails left on the phone of a kidnapped 13-year-old schoolgirl who was later found killed.

Both Hinton and Brooks deny knowledge of hacking at the News of the World. Brooks, who was arrested and released on bail Sunday, gave evidence to the committee after the Murdochs.

In one surprising disclosure, it emerged that News International had paid the legal fees of private investigator Glenn Mulcaire, who was convicted of hacking into the cellphones of aides to the royal family. Mulcaire is also suspected of intercepting and deleting messages on the phone of the slain teenager in 2002.

It was unclear whether News International was continuing to pay Mulcaire's legal fees in civil suits, but Murdoch said he would try to end the arrangement.